The visible burrow system: A view from across the hall

SUMMARYThe ecology of plague (Yersinia pestis infection) in its ancient foci in Central Asia remains poorly understood. We present field data from two sites in Kazakhstan where the great gerbil (Rhombomys opimus) is the major natural host. Family groups inhabit and defend burrow systems spaced throughout the landscape, such that the host population may be considered a metapopulation, with each occupied burrow system a subpopulation. We examine plague transmission within and between family groups and its effect on survival. Transmission of plague occurred disproportionately within family groups although not all gerbils became infected once plague entered a burrow system. There were no spatial patterns to suggest that family groups in close proximity to infected burrow systems were more at risk of infection than those far away. At one site, infection increased the chances of burrow-system extinction. Overall, it is useful to consider the burrow system as the unit of study within a much larger metapopulation.

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Influence of the semiaquatic habit in determining burrow structure of the star-nosed mole (Condylura cristata)

Canadian Journal of Zoology ◽

10.1139/z83-219 ◽

1983 ◽

Vol 61 (7) ◽

pp. 1688-1692 ◽

Cited By ~ 10

Author(s):

Graham C. Hickman

Keyword(s):

Food Storage ◽

Burrow System ◽

Active Nest ◽

Nest Chamber ◽

System A ◽

Burrow Structure ◽

Condylura Cristata

Condylura cristata is unique from most talpids in being semiaquatic. This report investigates the effect of a water habitat on burrow structure and is the first description of completely excavated burrow systems of the star-nosed mole, representing reedbed and lakeside habitats. Major features of the burrow structure included lack of surface ridges and mounds, unplugged burrows, along the edge of water, lack of steep vertical shafts to lower levels, deep tunnels not confined to particular areas of burrow system, a single active nest chamber containing dead leaves and freshly chewed pieces of Typha, and absence of special chambers for food storage or defecation. In comparing the influence of aquatic habits on structure of the burrow with terrestrial (Scalopus aquaticus) and aquatic (Desmana moschata) species of Talpidae, the semiaquatic Condylura is intermediate in position.

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New Design for a Differentially Pumped Hydration Chamber for a Siemens IA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006427x ◽

1971 ◽

Vol 29 ◽

pp. 44-45

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Electron Microscopy ◽

Water Vapor ◽

Electron Diffraction ◽

Water Vapor Pressure ◽

Biological Materials ◽

Thin Membrane ◽

Reliable System ◽

System A ◽

Water Films ◽

Aperture Opening

Electron microscopy and diffraction of biological materials in the hydrated state requires the construction of a chamber in which the water vapor pressure can be maintained at saturation for a given specimen temperature, while minimally affecting the normal vacuum of the remainder of the microscope column. Initial studies with chambers closed by thin membrane windows showed that at the film thicknesses required for electron diffraction at 100 KV the window failure rate was too high to give a reliable system. A single stage, differentially pumped specimen hydration chamber was constructed, consisting of two apertures (70-100μ), which eliminated the necessity of thin membrane windows. This system was used to obtain electron diffraction and electron microscopy of water droplets and thin water films. However, a period of dehydration occurred during initial pumping of the microscope column. Although rehydration occurred within five minutes, biological materials were irreversibly damaged. Another limitation of this system was that the specimen grid was clamped between the apertures, thus limiting the yield of view to the aperture opening.

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High-resolution electron microscopy of Cu2O surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143584 ◽

1986 ◽

Vol 44 ◽

pp. 396-397

Author(s):

V. Castano ◽

W. Krakow

Keyword(s):

High Resolution ◽

Natural Extension ◽

High Resolution Electron Microscopy ◽

Point Of View ◽

Initial Oxidation ◽

System A ◽

Resolution Electron ◽

Surface Reconstructions ◽

Atomic Surface ◽

Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

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Twin boundary structure of a Y-Ba-Cu-O superconductor

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152811 ◽

1989 ◽

Vol 47 ◽

pp. 168-169

Author(s):

Yimei Zhu ◽

Masaki Suenaga ◽

R. L. Sabatini ◽

Youwen Xu

Keyword(s):

Twin Boundary ◽

Fine Particles ◽

Imaging Techniques ◽

Fine Powder ◽

Orthorhombic Phase ◽

Boundary Structure ◽

Crystallographic Axis ◽

System A ◽

High Resolution Structure ◽

Electron Microscopes

The (110) twin structure of YBa2Cu3O7 superconductor oxide, which is formed to reduce the strain energy of the tetragonal to orthorhombic phase transformation by alternating the a-b crystallographic axis across the boundary, was extensively investigated. Up to now the structure of the twin boundary still remained unclear. In order to gain insight into the nature of the twin boundary in Y-Ba-Cu-O system, a study using electron diffraction techniques including optical and computed diffractograms, as well as high resolution structure imaging techniques with corresponding computer simulation and processing was initiated.Bulk samples of Y-Ba-Cu-O oxide were prepared as described elsewhere. TEM specimens were produced by crushing bulk samples into a fine powder, dispersing the powder in acetone, and suspending the fine particles on a holey carbon grid. The electron microscopy during this study was performed on both a JEOL 2000EX and 2000FX electron microscopes operated at 200 kV.

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Speech Therapy Services in a Large School System: A Six-Year Overview

Language Speech and Hearing Services in Schools ◽

10.1044/0161-1461.0704.207 ◽

1976 ◽

Vol 7 (4) ◽

pp. 207-219 ◽

Cited By ~ 3

Author(s):

Constance P. DesRoches

Keyword(s):

School System ◽

Speech Therapy ◽

Factors Affecting ◽

Case Load ◽

Number Of Children ◽

School Population ◽

System A ◽

Therapy Services ◽

And Shifts ◽

Selection Factors

A statistical review provides analysis of four years of speech therapy services of a suburban school system which can be used for comparison with other school system programs. Included are data on the percentages of the school population enrolled in therapy, the categories of disabilities and the number of children in each category, the sex and grade-level distribution of those in therapy, and shifts in case-load selection. Factors affecting changes in case-load profiles are identified and discussed.

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